Reserve for Losses and Loss Adjustment Expenses - Retroactive Reinsurance (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Deferred retroactive reinsurance gain at beginning of period	$ 86,720
Adverse prior year development ceded on subject business	14,189	$ (1,928)
Deferred retroactive reinsurance gain at end of period	100,909
Excess & Surplus Lines
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Adverse prior year development ceded on subject business	14,189	(1,928)
Commercial Auto LPT, E&S ADC And E&S Top Up ADC \| Excess & Surplus Lines
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Deferred retroactive reinsurance gain at beginning of period	86,720	57,970
Adverse prior year development ceded on subject business	14,780	144
Retroactive reinsurance benefits under the recovery method	(591)	(2,072)
Deferred retroactive reinsurance gain at end of period	100,909	56,042
Commercial Auto LPT \| Excess & Surplus Lines \| Commercial Auto LPT
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Deferred retroactive reinsurance gain at beginning of period	2,927	9,222
Adverse prior year development ceded on subject business	0	144
Retroactive reinsurance benefits under the recovery method	(591)	(2,072)
Deferred retroactive reinsurance gain at end of period	2,336	7,294
E&S ADC \| Excess & Surplus Lines
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Deferred retroactive reinsurance gain at beginning of period	83,793	48,748
Adverse prior year development ceded on subject business	0	0
Retroactive reinsurance benefits under the recovery method	0	0
Deferred retroactive reinsurance gain at end of period	83,793	48,748
E&S Top Up ADC \| Excess & Surplus Lines
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Deferred retroactive reinsurance gain at beginning of period	0	0
Adverse prior year development ceded on subject business	14,780	0
Retroactive reinsurance benefits under the recovery method	0	0
Deferred retroactive reinsurance gain at end of period	$ 14,780	$ 0